What is an acceptable packing temperature range?

Finally got the truck to draft and pump to well over new spec. Adjusting the packing was an incredibly precise maneuver... too tight ... packing gets hot... too loose, lose prime. Now we have it at a point where it runs at about 106 to 112 degrees Farenheit and ambient is 75. What is an acceptable rise in temperature for the packing during operations. I am using a Raytek IR thermometer to measure. I think that this method will give us a "heads-up" on a packing or an overheating issue before it becomes serious. This would not be for running all the time, just to use during inspection schedules.

Additionally I get the 10-12 drops leaking through the packing per minute while truck is under pressure from hydrant and pump is not running, but as soon as pump starts drafting and pumping, the dripping stops. Obviously I am getting some water through the packing, or I would have a temperature issue. My thought is that maybe the volute water may be partially working it's way into the pump suction chamber instead of into the outside when a vacuum is created while drafting. Any ideas or suggestions?

There is no acceptable temp range for pump packings that I have ever seen or heard of while in pump mode/gear. If you are not dripping or throwing water with the pump engaged, you need to find out why, and correct it. Otherwise you will burn up the shaft.

On a side note, I think your temp range is fine as long as you keep it below 150-ish. But that is just a guess.

Is there a way you can find a happy medium, to where it drips, and still catch a prime??

I have had this thing apart several times. I was wondering what would cause this. In fact what it is doing makes perfect sense (imho) ... assembly of the packing calls for... one segment of packing first, the 2 volute washers, packing, spacer, packing, spacer, packing, spacer, gland... In other words, one segment of packing preventing volute water from going into the pump, 3 segments of packing keeping the volute water from coming out the front. Am I missing something? Water is going to be far more willing to go back into the pump through that one segment of packing, specially with a vacuum being applied than to go outside. Or does there need to be so much flow going into the volute that no matter how much water is going back into the pump, you still have the 12 drops or so leaking out the front. Every time I try to do this, I lose prime and cease to pump and truck becomes a "Bit$%$#" to prime if at all.

thanks

Raul

Originally Posted by FIREMECH1

There is no acceptable temp range for pump packings that I have ever seen or heard of while in pump mode/gear. If you are not dripping or throwing water with the pump engaged, you need to find out why, and correct it. Otherwise you will burn up the shaft.

On a side note, I think your temp range is fine as long as you keep it below 150-ish. But that is just a guess.

Is there a way you can find a happy medium, to where it drips, and still catch a prime??

Scooter: This is still acting like the cooling line is plugged. A 6" long piece of 1/4" tubing should flow about 5 gpm at 100 psi. There should be more than enough water to pressurize the packing when operating. You are correct, that when the pump is turning, more water should flow along the shaft back into the pump, but there should still be enough to act as a lubricant along the outboard side toward the packing gland. Simply pressurizing the pump without turning the shaft just allows the water to flow from the pressurized eye along the shaft and out the gland. The position of the lantern ring must be directly beneath the cooling line to allow the water to reach the pump shaft. The first packing ring width and the spacers are critical dimensions.

got that, but it is possible that since this packing has been in and out a couple of times and looks ok, maybe it is just letting a lot more water back thatn out the front... I am going to let it pump a bit and watch the temp... seeking the drip... and if it does not happen... out it goes again and new packing gets installed... will recheck the alignment of the lantern rings... even though I am sure that they are right on the money (under the volute hole) and go from there... so close yet so far away... BTW volute hole is clear

Thanks again

Raul

BTW, the pressure relief indicator light system we discussed earlier works great with the check valve installed... drafting and hydrant... your post about hydrant pressure screwing things up saved the day... it now works and has a few seconds delay reporting status of valve... maybe tomorrow I will take pics and post if anybody is interested.

Originally Posted by KuhShise

Scooter: This is still acting like the cooling line is plugged. A 6" long piece of 1/4" tubing should flow about 5 gpm at 100 psi. There should be more than enough water to pressurize the packing when operating. You are correct, that when the pump is turning, more water should flow along the shaft back into the pump, but there should still be enough to act as a lubricant along the outboard side toward the packing gland. Simply pressurizing the pump without turning the shaft just allows the water to flow from the pressurized eye along the shaft and out the gland. The position of the lantern ring must be directly beneath the cooling line to allow the water to reach the pump shaft. The first packing ring width and the spacers are critical dimensions.